The present disclosure relates generally to hermetic barrier layers, and more specifically to sputtering targets and high-throughput physical vapor deposition methods for forming hermetic barrier layers.
Hermetic barrier layers can be used to protect sensitive materials from deleterious exposure to a wide variety of liquids and gases. As used herein, “hermetic” refers to a state of being completely or substantially sealed, especially against the escape or entry of water or air, though protection from exposure to other liquids and gases is contemplated.
Approaches to creating hermetic barrier layers include physical vapor deposition (PVD) methods such as evaporation or sputtering, and chemical vapor deposition (CVD) methods such as plasma-enhanced CVD (PECVD). Using such methods, a hermetic barrier layer can be formed directly over the device or material to be protected. Alternatively, hermetic barrier layers can be formed on an intermediate structure such as a substrate or a gasket, which can cooperate with an additional structure to provide a hermetically-sealed workpiece.
Both reactive and non-reactive sputtering can be used to form a hermetic barrier layer, for instance, under room temperature or elevated temperature deposition conditions. Reactive sputtering is performed in conjunction with a reactive gas such as oxygen or nitrogen, which results in the formation of a corresponding compound barrier layer (i.e., oxide or nitride). Non-reactive sputtering can be performed using an oxide or nitride target having a desired composition in order to form a barrier layer having a similar or related composition.
On the one hand, reactive sputtering processes typically exhibit faster deposition rates than non-reactive processes, and thus may possess an economic advantage in certain methods. However, although increased throughput can be achieved via reactive sputtering, its inherently reactive nature may render such processes incompatible with sensitive devices or materials that require protection.
Economical sputtering materials, including sputtering targets that can be used to protect sensitive workpieces such as devices, articles or raw materials from undesired exposure to oxygen, water, heat or other contaminants are highly desirable.